微量元素硒的研究与应用

介绍了硒在电子、颜料、玻璃、橡胶、塑料、冶金方面的应用概况，着重阐述了人体必需微量元素－硒及其在农业、医学方面的研究和应用。     

Finite element modeling of acoustic scattering from an encapsulated microbubble near rigid boundary

This article proposes a finite element model (FEM) for predicting the acoustic scattering from an encapsulated microbubble near rigid boundary. The validity of the model is first examined by comparing the acoustic nonlinear response of a free microbubble with that obtained by the Church model. Then this model is used to investigate the effect of the rigid boundary on acoustic scattering signals from microbubble. The results indicate that the resonance frequency decreases while the oscillation amplitude increases as the microbubble approaches the rigid boundary. In addition, the fundamental component of the acoustic scattering signal is enhanced compared with that of the free microbubble.     

Difference-frequency ultrasound generation from microbubbles under dual-frequency excitation

The difference-frequency (DF) ultrasound generated by using parametric effect promises to improve detection depth owing to its low attenuation, which is beneficial for deep tissue imaging. With ultrasound contrast agents infusion, the harmonic components scattered from the microbubbles, including DF, can be generated due to the nonlinear vibration. A theoretical study on the DF generation from microbubbles under the dual-frequency excitation is proposed in formula based on the solution of the RPNNP equation. The optimisation of the DF generation is discussed associated with the applied acoustic pressure, frequency, and the microbubble size. Experiments are performed to validate the theoretical predictions by using a dual-frequency signal to excite microbubbles. Both the numerical and experimental results demonstrate that the optimised DF ultrasound can be achieved as the difference frequency is close to the resonance frequency of the microbubble and improve the contrast-to-tissue ratio in imaging.     

离子液体及其在环境污染物分离分析中的应用

介绍了离子液体的制备方法和重要性能,综述了近年来离子液体在环境污染物分离分析领域中的应用情况。引用文献45篇。     

基于PAM/CS/MoS2复合水凝胶的QCM湿度传感器制备及应用

通过自由基聚合的方法，将二硫化钼(MoS₂)引入聚丙烯酰胺/壳聚糖(PAM/CS)水凝胶体系，制得互穿网络结构的PAM/CS/MoS₂复合高分子水凝胶。利用傅里叶变换红外光谱、拉曼光谱、扫描电子显微镜、激光扫描共聚焦显微镜对水凝胶的组分和形貌进行分析。利用万能试验机和接触角测量仪对水凝胶的力学性能和亲水性能进行测试，最后用石英晶体微天平(QCM)探究了该复合水凝胶薄膜在湿度传感领域的应用。结果表明，PAM/CS/MoS₂-0.4(MoS₂在体系中的质量为0.4 mg)复合水凝胶具有最大的压缩应力(584.6 kPa)与最大的压缩应变(83.8%);MoS₂的引入，增强了复合水凝胶的亲水性；随着环境相对湿度从11%增加到95%，基于PAM/CS/MoS₂复合水凝胶的QCM湿度传感器的响应频率最大可达2 642 Hz，相对湿度变化1%的灵敏度为31.45 Hz，有望应用于湿度传感领域。     

纳米材料在环境样品重金属分析中的应用

纳米材料具有大的比表面积,拥有优良的吸附性能,因此在环境分析领域的应用逐渐增多。对纳米材料吸附重金属的原理、影响吸附的主要因素以及纳米材料在环境样品重金属分析中的应用进行了综述,并对其发展前景作了展望。     

HPM视角下的“全等三角形角边角判定定理”教学

笔者从HPM视角下设计“全等三角形角边角判定定理”的教学,以泰勒斯测量海难船船距的故事引入,利用叠合法进行解释,增加《几何原本》中的反证法对判定定理进行说理,使学生对判定定理的理解从感性上升到理性认识.课后反馈显示,学生对所融人的数学史很感兴趣,基本理解了反证法,并且了解了数学的实践价值.     

4-氨基-1-丁醇的合成研究

使用四丁基溴化铵为相转移催化剂,以4-氯-1-丁醇作为起始原料,与邻苯二甲酰亚胺钾盐反应制备N-(4-羟基丁基)邻苯二甲酰亚胺(中间产物),中间产物在氢氧化钠的作用下水解得到4-氨基-1-丁醇。通过高分辨质谱、核磁共振谱等对中间产物和产品进行了测定和结构表征。考察了反应溶剂、4-氯-1-丁醇与邻苯二甲酰亚胺钾盐摩尔比、反应温度、反应时间、四丁基溴化铵与邻苯二甲酰亚胺钾盐摩尔比对中间产物收率的影响,优化反应条件之后4-氨基-1-丁醇最佳的总收率为77. 2%。此工艺路线具有合成方法简便、反应条件温和、产品收率高等优点,可以进行工业放大。     

选择性扩散和选择性吸附手性拆分膜及其应用

根据选择性分离机制的不同，介绍了选择性扩散和选择性吸附膜的手性折分机理及在手性化合物拆分中的应用，比较了两类膜在材料、制备方法、膜结构、膜性能、操作条件等方面的特点与差别。